Digital broadband broadcast networks enable end users to receive digital content including video, audio, data, and so forth. Using a mobile terminal, a user may receive digital content over a wireless digital broadcast network. Digital content can be transmitted in a cell within a network. A cell may represent a geographical area that may be covered by a transmitter in a communication network. A network may have multiple cells, and cells may be adjacent to other cells.
In the past, access from one cell to signals being transmitted in a neighboring cell has been challenging. When information of signals in a neighboring cell is desired, such access may be difficult to obtain without a large expenditure of time and power. For example, access to signals in a neighboring cell via an interaction network wastes time as well as power of the receiver.
U.S. application Ser. No. 11/339,527, filed Jan. 26, 2006, addresses this issue by disclosing systems and methods for detecting neighboring cells in a communication network based on transmission parameter signal data, which is referred to in DVB as Transmission Parameter Signaling (TPS) bits, received in a signaling frame. In one example, a signaling frame contains a field of TPS bits that indicate a type of the signaling frame. The type of the signaling frame may indicate the information carried in the signaling frame as information of a current cell or a neighboring cell. The signaling frame may further include information from a neighboring cell in the same network or a different network as the current cell.
In digital broadcast networks, such as DVB-T/H systems, it is possible to transmit two MPEG-2 transport streams (TS) in one broadband channel that is identifiable by a channel center frequency when hierarchical mode is in use. The signal is divided into a High Priority (HP) stream and a Low Priority (LP) stream. The HP stream is more robust and thus extends the reception possibilities. The LP stream is less robust, but provides more capacity for service to use.
Furthermore, in digital broadcast networks, such as DVB-T/H, transposers or gap-fillers may be used to transpose a DVB-T/H stream from one transmitting frequency into another without re-modulating the DVB-T/H stream. Transposed sub-cells of this type provide an inexpensive way to extend the DVB-T/H network coverage. DVB-T/H is discussed in this document as an example of a digital broadcast network. But various features in accordance with embodiments may be used in other digital broadband broadcast systems such as Digital Video Broadcast-Terrestrial (DVB-T), Digital Video Broadcast-Handheld (DVB-H), Digital Multimedia Broadcast-Terrestrial (DMB-T), Terrestrial Digital Multimedia Broadcasting (T-DMB), Forward Link Only (FLO), and any other existing or later-developed digital broadcast systems both standardized and proprietary.
When hierarchical mode is used in DVB-T/H, the receiver must know, in addition to the identification for a network, network_id, and identification for a cell, cell_id, the priority of the DVB-T/H stream (i.e., whether it is HP or LP) in order to be able to receive the correct transport stream. Due to this type of signaling scheme, the vast majority of implementations are not able to support hierarchical transmission. Also, since the cell_id and network_id are shared attributes of the HP and LP streams, the streams are not independent of each other.
The network_id, cell_id, and other parameters of a sub-cell are the same as in the sub-cell's “mother cell” because the same signal is simply shifted into another frequency. Since none of the parameter values are changed in the “original stream,” the original stream also has to contain the sub-cell parameters (including frequency) in a separate descriptor. Due to its signaling complexity, the sub-cells typically lack end-to-end support in DVB-T/H systems.
U.S. application Ser. No. 11/339,527 describes signaling DVB-H parameters within TPS bits. In that application, however, a relation of HP/LP streams and cell and sub-cells was adopted that is similar those relations as in present standard (ETSI EN 300 744 V1.5.1 (2004-11) Digital Video Broadcasting (DVB); Framing structure, channel coding and modulation for digital terrestrial television, downloadable at http://webapp.etsi.org/exchangefolder/en_300744v010501p.pdf) compliant DVB-H systems. In DVB-T/H systems, the signaling of hierarchical streams is done by means of additional parameters “priority” and “hierarchy” (in Terrestrial delivery system, these descriptors of the Network Information Table (NIT) are described in ETSI EN 300 468 V1.7.1 (2006-05) Digital Video Broadcasting (DVB); Specification for Service Information (SI) in DVB systems, downloadable at http://webapp.etsi.org/exchangefolder/en_300468v010701p.pdf). Further, the signaling of sub-cell(s) was done with an additional descriptor “cell frequency link descriptor” (in Terrestrial delivery system, this descriptor of the Network Information Table (NIT) is also described in ETSI EN 300 468).
As such, it would be an advancement in the art to address the limitations discussed above by more efficiently signaling network information in TPS bits.